How to Find Bathroom Toilet Model Numbers

Need to replace a toilet part or match a fixture? Your best first step is finding the toilet model number. Every manufacturer has their quirks, but we’ve broken it down so you can locate that model number fast—and get the right part without guesswork.

Why the Model Number Matters

Toilet model numbers help identify:

  • Replacement parts (like fill valves, flappers, and tank lids)
  • Compatible accessories (bidets, seats, and flush buttons)
  • Full toilet replacements with the same footprint or style

Where to Look (General Tips)

Here are some common places toilet model numbers hide:

  • Inside the tank – Look near the water line or stamped into the porcelain
  • Under the tank lid – Gently remove the lid and look on the underside
  • Behind the bowl or base – Occasionally, models are printed or engraved near the back

Use a flashlight—and maybe a little patience. Dust and hard water stains can cover up key info.

Brand-Specific Model Number Locations

Kohler
  • Location: Inside the tank, back wall
  • Format: Typically a four-digit number (e.g., K-4519)
  • Format: Typically a four-digit number (e.g., K-4519)
  • May be preceded by “K” or “Kohler.” The full toilet number may include additional digits for the tank/bowl combination.

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Mansfield

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Still Can’t Find It?

Sometimes the number wears off or is impossible to read. In that case, snap a photo of:

  • The inside of the tank
  • The toilet base
  • Any markings or logos

Then reach out to our team at SquarePeg »—we’re happy to help you match it up with the right part or full replacement.

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